Kepler-387 b
Astrophysical Synthesis & Habitability Characterization
Kepler-387 b is a confirmed terrestrial exoplanet orbiting the star Kepler-387, located approximately 2612.7 light-years (801.05 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0081% across the stellar disk), this world measures 1.03 Earth radii and has a measured mass of 1.08 Earth masses. Combining its mass and radius yields a mean bulk density of 5.45 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.02 g⊕ (10 m/s²), and an escape velocity of 11.5 km/s.
In its orbital architecture around Kepler-387, Kepler-387 b completes one full revolution every 6.792 Earth days at a semi-major axis of 0.068 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 108.9 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 994 K (+721°C / +1330°F) and receiving 304.08 S⊕ (~413,854 W/m²), Kepler-387 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-387 is classified as a stellar host with an effective photospheric temperature of 5,774 K, a radius of 1.046 R☉, a mass of 0.85 M☉, an estimated bolometric luminosity of 1.091 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.01 Gyr and a metallicity of [Fe/H] = -0.3 dex (metal-poor relative to the Sun). From Earth, Kepler-387 shines at apparent V-band magnitude 14.129 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-387 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-387 b sharing its stellar neighborhood alongside Kepler-387 c.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-387 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,774 K |
| Stellar Radius | 1.0460 R☉ |
| Stellar Mass | 0.8500 M☉ |
| Bolometric Luminosity | 1.091 L☉ |
| Metallicity [Fe/H] | -0.300 dex |
| Stellar Age | 1.010 Gyr |
| Apparent Magnitude | V: 14.129 · G: 13.935 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.068000 AU |
| Orbital Period | 6.792 days |
| Mean Orbital Velocity | 108.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5500° |
| Mean Bulk Density | 5.45 g/cm³ (11.5 km/s vesc) |
| Insolation Flux | 304.0810 S⊕ (~413,854 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2612.700 LY (801.052 pc) |